With rapid development of the flat panel display, the application of the thin film transistor (TFT) has achieved great recognition. The thin-film element is configured to replace with the external integrated circuit (IC) module so as to completely manufacture circuits with various functions on the system on panel (SOP) in flat panel display. This technology is widely developed for achieving some goals, for example, the product with thin, light and low cost and the high manufacturing yield.
In SOP technology, most function circuits composes of the unit circuit comprising TFT elements, for example, the phase inverter (or simply called inverter), the logic gate or the memory circuit, etc. The phase inverter is a key circuit unit for the most electronic circuits. The most common circuit unit of the thin-film phase inverter composes of a p-channel TFT and a n-channel TFT. When the signal with high level (1) inputs into the input terminal, the n-channel semiconductor transistor turns on so as to output the signal with low level (0). Oppositely, when the signal with low level (0) inputs into the input terminal, the p-channel semiconductor transistor turns on so as to output the signal with high level (1). As far as the function of the phase inverter is concerned, if the transmission rate of the n-type or p-type thin film transistor element with single channel is low, it will cause the decrease of the output gain of the entire inverter; Alternatively, the characteristic of the n-type or p-type thin film transistor element with single channel is not good, for example, the larger initial voltage, it will also cause the operation voltage of the inverter is more larger. Consequently, the conventional inverter circuit composing of the p-type and n-type thin film transistor with single channel must uses different manufactures and different element size to achieve the optimal circuit. Moreover, in the known technology, the material of the active layer used in the thin film semiconductor element used for manufacturing the glass substrate or the display panel is almost the inorganic amorphous or polysilicon material. However, the amorphous thin film has disadvantages as follows: the lower carrier mobility, the larger operation voltage and the unsteady electric characteristics. The polysilicon thin film has disadvantages as follows: the higher cost, the complicated manufacture and the device uniformity is not good and it difficult to perform mass generation. Thereby, it is a great challenge to develop the SOP technology.